2018 ASHS Annual Conference

Many recent studies report that broccoli has great anti-cancer activities because of high glucosinolates (GLs) contents, such as glucoraphanin (GLR) and glucoerucin (GLE). Previously we showed that broccoli microgreen contains high GLs than broccoli florets and mature leaves, indicating that microgreens is a richer source of GLs than mature broccoli. Preharvest calcium spray could significantly increase the total aliphatic GLS levels, while postharvest UV-B radiation only had limited effects on GLs enrichment. Here we report the impact of preharvest UV-B treatment on GLs levels in broccoli microgreens. Our results showed that preharvest UV-B treatments with 10 mM CaCl₂ spray could significantly increase the GLE, GLR, and total aliphatic GLs levels by around 70% in broccoli microgreens as compared to the control. Additionally, the nutritional qualities of two UV-B treated microgreens were quite stable during 21-day storage, with only small changes in their GLS levels. The UV 0.27 Wh/m² with 10 mM CaCl₂ spray treated broccoli microgreen maintained their overall quality, and had the lowest TEL and off-odor values during the storage. Furthermore, UV-B 0.27 Wh/m² treated microgreens significantly upregulated the level of GLs synthetic genes such as CYP79F1 during storage. Thus, the preharvest UVB is more effective on enriching the GLs levels than postharvest UVB. Overall, preharvest UV treatment together with calcium spray can enhance the health-beneficial compounds and improve the postharvest quality of broccoli microgreen.